Earth Science


Earth’s Evolution in 10 Minutes

Earth’s Evolution in 10 Minutes

  • pummel 揍,撞击
  • asteroids 小行星

Earth has been pummeled by asteroids, ruled by other life forms.

4.5 bllion years ago: solar system began to emerge out of a dense cloud of interstellar gas and dust. It became hoter and hoters, hydrogen and helium occurred and Sun was born. The clumps in the cooler regions of the Solar System were mostly made of ice, liquids and gases. Closer the the Sun, all the rocky material formed the inner planets.

Earth: spewed out gases like hydrogen, sulfide(硫化物), methane and carbon dioxide. These gases made up the very first atmosphere on our planet. Early Earth was constantly bombared by large asteroids and comets.

3.8 billion years ago: On this hot early earth, there were no oceans, all water existed as gas. After it cooled enough, water occured.

3.3 billion years ago: the first continents emerged from the ancient ocean. More and more land rose from the ocean.

2.4 billion years ago: Cyanobacteria evolved, to become our planets first photosynthesizers. Finally, we have oxygen producers, to make the Earth’s atmosphere muchu more hospitable. With less cabon dioxide in the atmosphere, the earth becomes icy cold. First ice age.

1.1 billion years ago: Ica Age. Continents reassembled into a super continet. Life became more complex. Pannotia formed.

540-485 million years ago: explosion of new life, called the Cambrian Explosion(寒武纪大爆发). Animals during the period had hard body parts like shells or spines. The most famous of all were the alien-looking trilobites(三叶虫, mentioned by FEIFEI in her Artificial Intelligence Course).

440 million years ago: the climate suddently shifted, and temperature of the ocean changed dramatically. Earth saw its first mass extinction event. This was the Ordovician-Silurian extinction. The majority of life (that had spreading across the planet) vanished. Many of these lifeforms laid the foundation for the ecosystems that we have on Earth today.

420-350 million years ago: First trees arose from Earth’s soil. And the first animal made their way to land too.

250 million years ago: the planet was covered by our last, vast supercontinent, Pangea(a whole big land on earth, the origin of plate tectonics). Earth witnessed the greatest mass extinction in out history, The Great Dying. Huge amounts of greenhouse gases and accelerated global warming wiped out about 90% of all species on Earth. But this mass extinction helped pave the way for the next wave of animals to evolve.

240-230 million years ago: the first dinosaurs appeared. For the next 150 million years, they’d rule the land. Pangea broken up forming the continents we know today.

66 million years ago: An asteroid slammed into our planet, right where Mexico sits now, and it coughed so much debris into the atmosphere that it blocked out the Sun. This led to devastating climate changes that caused the dinosaurs to die out.

6 million years ago: the earliest know humans started walking this world. This species was called Sahelanthropus(撒哈拉人,非洲).

6 million years ago: human walks up right.

5 million years ago: developed tools.

800, 000 years ago: humans controlled fire. They use fire to cook food and get warm. Their brains continue to evolve, now more rapidly than ever. Learned to interact with each other.

40,000 - 15000 years ago: all other human species besides Homo sapiens(智人) went extinct.

10,000 years ago: Earth saw its earliest farmers. These previously nomadic humans stopped wandering the planet and finally put down their roots.

Jumping way forward to about 250 years ago, the Industrial Revolution took place. We went through major technological, socioeconomic and cultural transformations. Rural, farm-based societies became more industrialized, urban ones. Our human population continue to grow.

By 1804, we reached one billion. By 1927, we’d hit two billion. And since the 1960s, the global population has risen faster and faster.

Climate change, temperatures and sea levels are rising worldwide, and biodiversity is declining. We could be on the vergy(edge) of another mass extinction event if things don’t change.

Human Evolutions

  • single cell
  • gene
  • Sex: sex introduces variation, genes from two cells
  • Mutation: increase differences, until cells become so different, they seperate species
  • mutating and diversifying, eyes developed, light sensitive
  • nerve cells
  • fish-like creature, brain
  • jaws, teeth
  • foot long armored fish
  • bleak 苍凉,黯淡
  • breath air, new organ
  • lungs and gills 肺和鳃
  • hiccups 打嗝
  • swamp 沼泽
  • leave water, for new life on land
  • perish 毁灭
  • Egg: in a touch shell with all the nutrients the embryo needs 在触摸外壳中,含有胚胎所需的所有营养
  • Sex is the best way to increase genetic variety and keep our species alive.
  • brain evolved
  • molten rock
  • volcanic eruptions wiped out 95% of all living things
  • goosebumps 起鸡皮疙瘩
  • new structure in brain: neocortex 新皮质, the home of complex thought, allows us the analyze a situation and respond, it will one day give us power the imagine, create, and communication
  • evolve to give birth to live young, instead of egg. we nurture them with milk(哺乳动物,体内孵化)
  • sweat glands evolve to become mammary glands 乳腺
  • the birth of new kind of animal
  • mammals have arrived 哺乳动物
  • dinosaur lived for 150 Million years
  • rat-like mammals
  • gorge 饱食
  • After the extinction of dinosaurs, mammals became the dominant animals on land.
  • new life began to sprout, fruit ripens on the trees.
  • primates 灵长类动物(56 million years ago)
  • ravage 蹂躏
  • natural selection
  • stretch arms
  • Africa, 4.4 million years ago, walking
  • can walk further and faster
  • finding food, mate, shelter
  • improve brain power, brain biger and biger
  • handyman, first man
  • made the very first tool
  • East Africa, we are the first species to make tools
  • use stone smash bones
  • hunters work with other members
  • Fire, keep warm, cook food, live longer
  • family life
  • cooked meat
  • brain increase
  • words, speech, language
  • 200, 000 years ago, Homo sapiens, wise man, largest brain, tools.
  • We become the undisputed maters of the world.